Boiler plug



May 22, 1923. 1,456,315

F. E. KEY I BOILER PLUG Filed May 27. 1918 knvanhor'. I F. E. Key

Patented May 22, 1 92 13.

FREDERICK E. KEY, 013' ST. LOU-IS, MISSOURI, ASSIGNOR T0 KEY BOILER COMPANY, or s'r. Louis, MISSOURI, A oonronar'ron or rssdunr.

BOILER PLUG.

Application filed May 27, 1918. Serial No. 236,912.

One of the objects of this invention is to simplify and to otherwise improve the earlier device, so that the plug can be more easily tightened in a boiler, and more securely held in firm contact with its seat. Another object is to provide a simple and inexpensive safety device whereby the plug is secured to the boiler.

In accordance with the preferred form of the invention, the new device comprises a tapered hollow plug, closed at its inner end and open at its outer end to receive an expanding device. The new plugs are intended more particularly for use as closures for the hand holes of boilers, these holes being circular openings formed in a wall of the boiler, and they are preferably tapered to provide tapering annular plug-receiving seats. The tapered plugs may be very easily and quickly inserted into the tapered openings, and owing to the peculiar manner in which the different elements are combined with each other, the plugs, acting like check valves, are forced onto their tapered seats by the boiler pressure on their closed inner ends.

To positively secure the plugs to the boiler, thereby preventing them from being accidentally displaced from their tapered seats, the open outer end of each plug is preferably provided with detachable retaining devices which can be easily applied and removed from the exterior of the boiler.

Fig. I is a vertical section showing one of the plugs applied to a wall of the boiler.

Fig. II is an end view of the plug.

Fig. III is a vertical section, on a reduced scale, showing a portion of the water leg of a boiler equipped with the new plugs.

The water leg shown in Fig. III has an inner wall 1 to which the tubes 2 are applied, and an outer wall 3 provided with the usual hand holes through which the tubes may be inserted.

A designates one of the plugs for closing the hand holes. Each plug A is a hollow sheet metal member closed at its inner end by a bowed wall 4- having a convex face, which is exposed to the-pressure of the boiler, a bowed wall of this kind being well adapted to resist such pressure. The outer end of each plug is open to receive an expanding device, which may be used for the purpose of tightening the plug on its seat. y'The hollow plug A. has a tapered, or conicocylindrical, portion 5 which extends from the bowed wall 4 to the outer end of the plug. The conico-cylindrical portion 5 gradually decreases in diameter toward the open outer end of the plug, so that the pressure in the boiler will tend to force the plug onto its seat.

In the earlier patent to which I have referred the plug-receiving holes are not tapered, andthe open end portions of the plugs are formed in a peculiar manner to contact with an expanding device whereby the plugs are forced onto their seats. In actual practice I have found that it is notv difficult to taper the holes and. that much better results are obtained by making the holes conform to the taper of the plugs. The wall 3 is therefore provided with tapered plug-receiving openings, providing tapered annular seats which conform to the taper of the plugs, as shown most clearly in Fig. I.

The plugs are inserted into the hand holes from the interior of the boiler, and then forced into engagement with their seats either by hammering the closed inner ends of the plugs or by the operation of an expander, which may be introduced into the open outer ends of the plugs. I prefer to first hammer the plugs on their closed inner ends, and to then use an expander merely for the purpose of tightening the plugs on their seats and not for the purpose of ma-' terially expanding the plugs. The expander can be used to remove irregularities, making the plug firmly contact with its seat, without materially enlarging the diameter of the plug.

When the plug is in service it is seated like a check valve. The pressure of the boiler, acting upon the closed inner end of the plug, firmly forces the tapered portion of the plug ontoits tapered seat. The closed inner end of the plug is so large that the boiler pressure cannot force the plug entirely through the tapered opening.

The annular open outer end portion of the plug extends from the wall 3 of the boiler, and this extended portion may be provided with transverse pin-receiving openings 6 (Fig. 1) adapted to receive safety devices 7, preferably in the form of cotter pins which extend through said openings 6 and project from the periphery of the plug. These detachable pins 7 can be easily and quickly manipulated from the exterior of the boiler, and they constitute a very simple and inexpensive safety device whereby the plug is positively secured to the boiler. If the workman should fail to tighten the plug, or if a plug is accidentally struck from the outside and thereby displaced or loosened, the pin 7 will positively prevent the plug from falling into the boiler, and the steam pressure in the boiler will tend to force the plug into firm engagement with its seat.

Iclaim:

l. A device of the character described, the combination of a wall member having a circular opening providingan annular plugreceiving seat, a hollow sheet metal boiler plug closed at its inner end and open at its outer end, said boiler plug having a smooth annular conico-cylindrical peripheral portion adapted to frictionally engage said annular seat, said conico-cylindrical portion being so tapered as to decrease in diameter toward the open outer end of the plug so that the plug, acting like a check valve, may be forced into frictional engagement with its seat by outward pressure on its closed inner end, the annular open outer end portion of the plug being adapted to pass through and extend from said opening, and a safety device preventing accidental inward displacement of the plug from said opening, said safety device comprising a detachable retaining device extending entirely through the wall of the last mentioned end portion and projecting from the peripheral face thereof at a point in front of the outer face of said wall member to retain the plug in said opening.

2. In a device of the character described, the combination of a wall member having a tapering opening providing an annular ta pering plug-receiving seat, a hollow sheet metal boiler plug closed at its inner end and open at its outer end, said boiler plug hav ing a smooth annular conico-cylindrical peripheral portion conforming to and adapted to frictionally engage said annular tapering seat, said conico-cylindrical portion being so tapered as to decrease in diameter toward the open outer end of the plug, so that the plug, acting like a check valve, may be forced into frictional engagement with its seat by outward pressure on its closed inner end, the annular open outer end portion of the plug being adapted to pass through and extend from said opening, the last mentioned end portion comprising an annular wall provided with a transverse pin-receiving opening, and a safety device comprising a cotter pin extending entirely through said pin-receiving opening and projecting from the periphery of the plug at a point in front of said wall member so as to prevent inward displacement of said plug.

In testimony that I claim the foregoing I hereunto afix my signature.

FREDERICK E. KEY. 

